Efficiency enhancement of DSSCs based on sol-gel prepared ZnO nanoparticles through cosensitization with natural and synthetic pigments

This study explores the effect of co-sensitizing dye-sensitized solar cells (DSSCs) based on ZnO nanoparticles with natural pigments from Nerium (oleander) and Ziziphus jujuba (jujube) fruit peel, alongside the synthetic pigment N719, to enhance efficiency. ZnO nanoparticles were synthesized via the sol-gel method, and five DSSC samples (DS1-DS5) were fabricated using the Doctor Blade technique. These were sensitized with: (1) jujube extract (D1), (2) Nerium extract (D2), (3) N719 (D3), (4) a blend of D1 and D2 (D4), and (5) a co-sensitized mix of D1, D2, and N719 (D5) in a 1:1:2 ratio. Structural and optical properties were characterized using FE-SEM, XRD, and UV–Vis spectroscopy, while photovoltaic performance was evaluated with a solar simulator. Results revealed that DS5, co-sensitized with all three pigments, exhibited the broadest absorption spectrum (200–600 nm) and the highest efficiency (3.28 %), attributed to enhanced light harvesting and electron transfer. The ZnO films showed a uniform, porous structure with an average nanoparticle size of 42.16 nm. This co-sensitization approach, combining low-cost natural dyes with N719, offers an eco-friendly and efficient strategy for improving DSSC performance.